Introduction to 46 XY DSD: 5 αRD and AIS

Differentiation and development of internal and external male genitalia is under the influence of several genes and endocrine factors. The defect at any step in this pathway may result in abnormal sexual differentiation and development described as DSD. It is a group of uncommon congenital conditions in which the development and differentiation of chromosomal, gonadal and anatomical sex is discordant and covers a wide spectrum of phenotypes.Ambiguous genitalia results from either excess androgens in a genetic female or deficiency of androgen in a genetic male. There are a number of situations where this can happen. CAH is the most common form of 46,XX DSD. Androgenic exposure in utero causes virilization irrespective of the genetic sex. Also in absence of androgens an XY child will look like a female at birth. Therefore a child with ambiguous genitalia could be a virilized female or an under-masculinized male.